Telegraphy



C. E. HAY.

TELEGRAPHY.

APPHCATION HLED NOV. 14, 1916.

2 SHEETSSHEET I.

C. E. HAY.

TELEGRAPHY.

APPLICATION FILED NOV. 14. I916. 1,357,199, Patented Oct. 26,1920.

' 2 SHEETS SHEET 2.

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arre CHARLES EDWARD Inna, or Essen, ENGLAND.

TELEGRAPHY.

Specification of Letters Patent.

Patented'Oct. 2c, 1920.

Application filed November 14, 1916- Serial No. 131,235.

To all whom it may concern:

Be it known that I, CHARLES EDWARD HAY, a subject of the King or"England, residing in Essex, England, have invented certain new anduseful Improvements in Telegraphy, of which the following is aspecification.

This invention relates to systems of telegraphy of the kind in which aperiodically varying voltage is constantly impressed upon the signalingcircuit, and is modified to constitute a signal.

The present invention is of a telegraphic system of the kind described,wherein the means to energize the signaling circuit is such as toimpress thereon a sine-wave or other smoothly changing periodic voltageand the arrangement is characterized by being such that the -frequencyof the voltage is not changed by the act of signaling; in result avoltage curve is obtained having substantially uniform horizontalspacing for each whole period. The object of this arrangement is toavoid the disturbance of the duplex balance which arises from a changein the frequency.

revision is made according to this invention for effecting a signal bymodifying the internal electromotive force of the generator whichsupplies the signal impulses, or, alternatively, by modifying theposition of the earthing. point relatively to the extreme positive andnegative points in the generator; again, alternatively, both thesemethods may be employed in combination. The said modification of theposition of the earthing point is conveniently eii'ected by providingthe generator-with one or more tappings each of which may be connectedto earth or otherwise brought to zero poten tial at will.

In one embodiment of this invention an oscillatory electrical circuit,maintained in oscillation by impulses from a battery through asynchronously driven reversing commutator is employed as the generatorand means are provided to earth at will one of a number of selectedpoints on the battery. 1

One method of carrying out this invention is illustrated in theaccompanying drawings in which Q I Figure l is a diagrammaticrepresentation of the apparatus and electrical circuits;

Fig. 2 is a perspective view of a detail of part of the apparatus ofFig. 1;

Fig. 3 is a diagram illustrating the kind of slgnal transmitted by theapparatus of F 1g. 1;

Fig. 4 is a perspective diagrammatic view oi a preferred construction ofa detail, and

F 1g. 5 is a diagram, explanatory of an arrangement illustrating thefundamental principle of this invention, and

Figs. 6, 7 and 8 are diagrams of signals sent by the arrangementof Fig.5.

Referring first to Figs; 1, 2 and 3, the point of junction A of thetelegraph cable A, and artificial line A, connected for dupler; work isconnected to a point between an inductance B and a condenser C which areconnected together to constitute an cecillatory circuit, which circuitis completed through an earth connection C,, an earth connection C and acommutator D, a battery being inserted in the manner hereinafter to bedescribed between the commutator D and earth connection C The commutatorD comprises two sections of the general shape indicated in perspectiveat D, in Fig. 2, and is provided with three brushes, namely the brush Econnected to the inductance B and the brushes E, and E, connectedrespectively to the tongues F, F, of relays G G .The relays Ga, G areenergized from battery G and the tongues F, F, play between contacts tocontrol, the current from a battery subdivided into four portions H, J,H, J,, all in series with one another, the center point H of which isconnected to earth by the connection A perforated tape K of thewell-known kind cooperates with brushes, or, as they are commonlycalled, prickers, K, K, to complete the circuit of the battery G througha metallic platform J over which the tape K travels in the direction ofthe arrow 7c. n

The upper contacts of the relays G G are connected to the free ends ofthe batteries J, J, respectively, while the lower contacts of theserelays, toward which the tongues are spring-impelled, are connected tothe junction points of the battery J with h, and the battery J with H,respectively.

The commutator D is driven by means of a small motor D which also servesto drive a sprocket-wheel D engaging with the center perforations of thetape K, the gearing D between the motor and the wheel D be ing such thatthe commutator makes one complete revolution during the time the tapetakes to move a distance equal tothat separating two successive holes ofthe center row of perforations.

On either side of the said center row, which row is. exclusivelyemployed for the purpose of shifting the tape, are other perforations,hereinafter referred to as the sig naling perforations, the row whichcooperates with the pricker K being intended to transmit dashes and thatwhich cooperates with the picker K being intended to trans mit dots.

The operation of the apparatus depicted in Fig. l is as follows. Theinductance B and condenser G when closedupon themselves through thepoint A and the earthing connections C C constitute an oscillatorycircuit which has 'a natural period of its own, but this natural periodis modified by the cable A, and line A together with theirappurtenances, being connected to the circuit at the point A. and alsothrough the earth connection (3,. The oscillatory circuit with theconnected parts therefore possesses a natural period of oscillationdifferent from that which it would have if it consisted simply of theinductance l3 and condenser C.

The motor D, is speeded up to drive the commutatorD so that itmakes onecomplete revolution in precisely the time of the said modified period.

Under normal conditions, whenqthe cir cuit is not bein employed to sendsignals, the two tongues F F of the relays both rest upon their lowercontacts.

Under these conditions the batteries H H are connected alternately tothe 0scillatory circuit through the brushes E E and i the brush E, bythe operation of the commutator. The batteries H H serve to maintain theoscillations in the circuit including the inductance B and condenser 6,with the result that a sinusoidal-wave of electro-motive force isimpressed upon the sending circuit, as is indicated at L in Fig. 3.

When, however the tape causes one of the prrickers to make contact withthe platform one of the relays G G is operated. As

illustrated in Fig. 1 the pricker K is cooperating with one of thesignaling perforations for a dot to close the circuit from the battery Gthrough the relay G and metallic platform J and the tongue F of thelatter is thus pulled against its upper contact. The battery J, inaddition to the battery H is thus put on to the brush E and, as thecommutator revolves to put the brushes E E into conducting connection,the battery J also is applied to the oscillatory circuit. and increasesits negative amplitude,

thus producing a signal such as is indicated in the space L of therecord shown in Fig. 3. A series of signaling perforations 00- operatingwith the pricker K would give a series of repeated signals, similar tothat in the interval L On the other hand, a series of signalinperforations cooperating with the prickei-T 1 would produce a series ofsig nals such as those indicated at L, in Fig. 3, since the relay G willnow be operative to lift its tongue F while the tongue F will havefallen back upon its lower contact.

In the well-known manner the signalin. dicated at L may represent adot'while each of those indicated at L, may represent a dash. .Thecombination of L and L represents the letter A, while the second one atL followed by three similar to that at L represents the letter B and theremaining four signals of Fig. 3 represent the letter G in the customarymanner.

it isrto be understood that the relays G and their tongues F F playingbetween fixed contacts are merelygiven in a digrainmatic sense toexplain the operation. The butting contacts of oscillatory tonguesplaying between fixed points do not conduce to the best working, owingto the liability of the tongues to chatter upon the contacts. ispreferred to employ, instead of tongue playing between two contacts, acommutator upon which there rest two brushes, and, cause the relay tolift one or the other of the said two brushes instead of moving a tongueover from one contact to another. Such an arrangement is indicateddiagrammatically in Fig. 4: as applied to therighthand half of theapparatus of Fig. 1. The relay coil G is there shown controlling thepositions of two brushes M 'M to cause one or other of them, but onlyone, to rest upon a contact wheel M which is connected by a third brushM to the brush E of the commutator D. The brush M is connected to thepoint of junction between the batteries H J and normally rests upon thewheel M, whereas the brush M, is connected to the free end of thebattery J and is substituted for the brush M, by the action of the relayG when excited. The brushes M, ill", are suitably insulated from oneanother and the operation of the armature G, of the relay so adjustedthat only one'of these two brushes at a time can make contact with thewheel M. Thus in the position shown the batteries H J, in series withone another are in readiness to be applied to the oscillating circuitthrough the brush E so soon as the commutator D enables this to occur.

As a result when a tape perforated as is the one shown in Fig. 1 passesthrough the apparatus the signals sent are those indicated in Fig. 3,the wave with a high crest at L, being due to the pricker in, being incontact with the platform (l.

A feature which lies at the root of the present invention is thatbywhich the Sig naling is etl'ected by the operation of-varying at thesending end, the point in the oscillations which is at zero potentialand thereby varying the distribution of linepotential' at the receivingend, Incrder to render this clear an arrangement embqdyingthe inventionin a more simple manner than the arrangements of Figs. 1 to 4 is shownin the diagram of Fig. 5.

In Fig. 5 a battery is connected by its middle point it to the uppercontact of a relay g, by its positive end H to the brush E, of thecommutator D, and by its negative end 71 to the brush E of thecommutator I). These parts D E, and E, are as in Figs. 1 to at, as arealso the parts A, A,, A,, B, C, C, and E.

he terminal it, of the battery is connected to the lower contact of therelay 9, and the terminal 7L2 to the lower contact of a relay The tongueof the relay g, is connected to the upper contact of g, and the tongueof is connected to earth. Each of these tongues is normallyspring-pressed against its upper contactand the circuits of the relaywindings are controlled by tape machines or in any desired manner.

When the parts are in the positions shown in Fig. 5 the impulses beingsent are as shown in Fig. 9 since the rotation of the commutator (whichis effected as shown in Fig. 2) )uts it, and alternately in connectionwith it and maintains an equal and symmetrical distribution of potentialabove and below zero by the aid of the oscillator constituted by theparts B and C. It now the tongue of relay g, be drawn on to its lowercontact the end h, of the battery is put to earth and signals as at Fig.7 are sent. If the tongue of is drawn down, however, instead of that ofg, the signals sent are as at Fig. 8. If both tongues happen to be downtogether the result is the same as if that of 9, alone were down. Itwill thus be clearly seen that the signals are effected entirely bychanging the zero potential point and thus changing the distribution ofthe potential. The signals of Fig. 6 are read as spaces, those of Fig. 7as dashes and those of Fig. 8 as dots.

A further advantage of the system according to this invention is that,when applied to printing telegraph systems, for example to the Baudotprinting telegraph, it overcomes the present diihculties arising fromthe sending and receiving end getting out of synchronisni. lVith thepresent invention, when such a printing system has been synchronized itremains in synchronism iLIlCllS not thrown out by the signalingoperations.

he reason for this is that when the sending of signals is effected bythe sudden application and removal of an electro-motive force to andfrom the line so that the graph of the sending impulses has theappearance of fiattopped rectangular waves, the tendency is Ior theimpulses at the receiving end to merge into one another so thatinpractice asmuch as 2 0% of each revolutlon of the Bandotdistributeristaken up with the operation of synchronizing the sendingand the receiving apparatus. 011 the other hand when the sendingimpulses are in the form of sine waves of potential, they are receivedat the far end in the same form, with. the result that each impulseserves to contribute its own share to the synchronization.

In either of the arrangements, namely that shown in Fig. 1, or thatshown in Fig. 4, the generator represented by a subdivided battery forenergizing the oscillatory circuit may be replaced by any othersub-divided generator, or suitably subdivided source of electromotiveforce.

W hat I claim as my invention and desire to secure by LettersPatentis 1. In a telegraph system the combination of an oscillatoryelectrical circuit operatively connected to a telegraph line so as toimpress thereon a voltage derived from oscillations in the saidcircuit,a sub-divided battery and a commutator operated at such a speed as toconnect the battery to the oscillatory circuit at intervals whichsynchronize with the natural period of that circuit and said linejointly when connected together, and means to select automatically thepoint on the battery which the commutator serves to connect to theoscillatory circuit.

2. In a telegraph system, a telegraph line, an oscillatory electricalcircuit operatively connected to the telegraph line so as to iln pressthereon a voltage derived from oscillations in the oscillatory circuit,a generator provided with tappings to give a plurality of diversevoltages, a commutator connecting the generator with the compoundcircuit formed by the said oscillatory circuit and telegraph line, meansto drive the commutator .at such a speed that the generator isperiodically connected to the said compound circuit synchronously withthe natural period belonging to that circuit, and means to select atwill which of the said tappings constitutes a second connection betweenthe generator and the said compound circuit.

3. In a telegraph system, a telegraph line, an oscillatory electricalcircuit operatively connected to the telegraph line so as to i1npressthereon a voltage derived from oscil' lations in the oscillatorycircuit, a generator provided with tappings to give a plurality ofdiverse voltages, a commutator connect- 'ing the generator with thecompound circuit formed by the'said oscillatory circuit and telegraphline and constructed to connect the compound circuit with two differenttappings from the generator alternately, means to drive the commutatorat such a speed that the generator is periodically connected to the saidcompound circuit synchronously with the natural period belonging to thatcircuit,

and means to select at will which of the saidtappin'gs constitutes asecond connection between the generator and the said compound clrcult. 1

Q In testimony whereof I have signed my name to this specification inthe presence of tWo subscribin Witnesses.

CH RL-ES EDWARD HAY. Witnesses: V v j HAROLD H1 SIMMoNs,

J OHN GAMERON'RENNIE;

